The Hohokam Observatory located on Shaw Butte is in the North Mountain Area of the Phoenix Mountain Preserve. The site has a sophisticated arrangement of petroglyphs, boulders and rooms that have been shown to mark the movement of the sun through the year. These observations would have been used by the Hohokam to properly time their various annual ceremonies. Visitors to the site should be very careful not to move any rocks or do anything that might disturb or damage the site.

The trailhead is located off of West Thunderbird Road at the end of Central Avenue. The parking lot is small and cars parked on the neighborhood streets will be towed. Abundant parking is available at the North Mountain Visitor Center at 12950 N. 7th Street about a half mile away. The Visitor Center has restrooms, a gift shop and various displays of interest.

Drinking water is available at the trailhead and at the Visitor Center.

From the trailhead follow the road to the right. The trail to the left leads over to the Visitor Center. A kiosk at this junction has a good map of the area. Hikers can also print out a map before hand by visiting the parks official website. The knob hill where the observatory is located is pointed to in this photo.

The trail climbs on a fairly steep slope to reach the site.

After a switchback or two the trail reaches the crest of the first ridge where off to the left a brown sign is visible that marks the archaeological site.

The rocks that form the walls for each of the rooms were dry stacked without the use of mortar to hold them in place. The rooms were laid out at specific angles and places in relation to the solar, and perhaps lunar, cycles.

A large boulder that has a number of circles with dots in the middle occupies a central point of the site. It has been shown that each of the solstices and equinoxes can be witnessed by the courses of light and shadows as they dissect or highlight particular images on the boulder.

Numerous other rocks also have petroglyphs that confirm the observations made on the large boulder. Even the alignment of several of the rooms have astronomical significance by marking the rising and setting of the sun at the solstices. With so much depending upon the position and orientation of certain rocks and the alignment of the rooms you can see how important it is that care should be taken while visiting the site.

It is a little surprising that an important site like the Hohokam Observatory on Shaw Butte isn't a little more developed with interpretive signs and any necessary site protections. Most visitors will only see unimpressive piles of rocks and faded petroglyphs and never realize the true value and significance of what lies before them. With a little information instead of shrugging off the site visitors can leave with an appreciation of it and respect for it. Various websites go into more detail of the observatory one of which can be found here. If you would like to see it for yourself then all you have to do is 'Take a hike'.